Copper base alloys containing manganese and aluminium



United States Patent 3,134,669 CiPPIER BASE ALLOYS CONTAINING MANGA- NESE AND ALUMINIUM Warner Jan ale Putter and Gerardus Petrus Knuvers, both of Drunen, Netherlands, assignnrs to Lips N. V., Drunen, Netherlands, a Dutch corporation No Drawing. Filed June 11, 1962, Ser. No. 201,292 Claims priority, application Netherlands June 13, 1961 Claims. (Cl. 75-161) This invention relates to copper base alloys containing manganese and aluminium, and shaped articles, particularly ships propellers, manufactured from such alloys.

Alloys are known which contain from 2 to 4% iron, 1 to 6% nickel, 3.5 to 9.5% aluminium, 15 to 35% manganese, with the balance being copper and incidental impurities.

Because such alloys have good mechanical characteristics and a good corrosion resistance, they have been proposed as a material for the manufacture of ships propellers. However, they are relatively expensive and the need is felt for cheaper alloys having at least the same or better characteristics.

With this object in mind, it is now proposed, according to the present invention, to prepare an alloy of this kind having the following composition: 1 to 9% iron, up to 7% nickel and up to 7% cobalt, wherein the total amount of nickel and cobalt taken together is not more than 7%, the three preceding elements when added together amounting to from 3 to 14% of the total weight, 3 to 9% aluminium, 17 to 21% manganese, 1 to 7% zinc, with the balance being copper and the usual impurities.

The alloy prepared according to the present invention has a low melting point, a high impact strength and a very good corrosion resistance, particularly in turbulent seawater.

In the copper alloys of the prior art which contained manganese at a level of between 17 and 21% and which also contained aluminium, which alloys have to satisfy high requirements of mechanical strength, zinc has never been added. It has been the opinion of the experts that the addition of Zinc in a higher quantity than that normally encountered as an impurity was unallowable. It has surprisingly been found that Zinc, when added to such alloys, has a good effect on several of the abovementioned characteristics. Moreover, zinc decreases the melting point of the alloy, which decrease is of importance in View of the resulting heat economy.

Additionally, copper-zinc alloys have become known in the art which contains 6 to 20% manganese, 0.1 to 5% iron, 0.1 to 8% nickel and at the most 1.5% aluminium. They are such for bearing sleeves or bushings and similar shaped articles which are subject to sliding friction. The prevailing opinion has been that a higher aluminium content for such alloys would cause the alloys to be much less workable, particularly when cold.

It has been surprisingly discovered that the Workability of alloys prepared according to the present invention is quite suflicient for most applications.

The requirement that the total amount of nickel and iron (and possibly cobalt) in the alloys prepared according to this invention should be from 3 to 14% of the total weight is related to the fact that the corrosion resistance in this range is best.

Preferably, the alloys prepared according to this invention contain a total of less than 0.008% arsenic, antimony and/or phosphorus. However these elements when present in higher quantities as usual impurities, do not have much unfavourable influence on the desired characteristics of the alloys.

3,134,669 Patented May 26, 1964 "ice Preferably an alloy prepared according to this invention has the following composition: 1 to 6.5% iron, 1 to 6.5% nickel, the two preceding elements taken together constituting 5 to 9% of the total weight, 3 to 9% aluminium, 17 to 21% manganese, 2 to 5% zinc, with the balance being copper and incidental impurities.

More particularly it is preferred to select the composition as follows: 3 to 5% iron, 1 to 3% nickel, 4.5 to 6% aluminium, 17 to 21% manganese, 3 to 5% zinc, with the balance being copper and the usual impurities. This preferred alloy is relatively soft and ductile and has a high elongation.

If it is desired to manufacture an alloy which is relatively hard, the aluminium content is preferably between 6.5 and 9%.

The invention can be realized by melting the components together in a metallurgical furnace in the conventional manner.

Example I The following elements were melted together in a suitable furnace: 6.06% iron, 2.00% nickel, 5.40% aluminium, 17.52% manganese, 3.31% zinc with the balance being copper and incidental impurities.

The alloy was cast into a bar in a sand mold, which bar was suited as a blank for extruding long profiles therefrom. The bar was allowed to cool slowly. Examination of a sample of this alloy gave the following values.

Tensile strength 63.2 kg. per square mi]li meter. Elongation at rupture 31.6%

Impact strength (notched) According to Charpy 8.1 kg. meter per square centimeter. Accordingto Izod 5.6 kg. meter per square centimeter.

The deformability and workability at high and normal temperatures and the Weldability were good.

Example 11 Following the same manner used in Example I, an alloy was obtained by melting together: 3.0% iron, 2.13% nickel, 4.97% aluminium, 20.1% manganese 3.92% Zinc, with the balance being copper and incidental impurities. The alloy was cast in a sand-cement-mold to a ships propeller.

Examination of a sample of this alloy gave the following values.

Tensile strength 72.5 kg. per square millimeter. Elongation at rupture 24%.

Impact strength (notched):

According to Charpy 7.6 kg. meter per square centimeter. Accordingto Izod 5.3 kg. meter per square centimeter.

The deformability and workability at high and normal temperatures and the weldability were good.

For both the above examples, the corrosion resistance in turbulent sea water flowing at high speed appeared to be excellent.

The above examples only serve to illustrate the invention and it will be clear that the invention is not restricted thereto and that several other embodiments are possible within the scope of the appendant claims.

All percentages given in this specification and in the claims are percentages by weight.

Q1! What we claim is:

1. A copper base alloy containing manganese and aluminium, having the following composition: 1 to 9% of iron, up to 7% nickel, up to 7% cobalt, nickel and cobalt together not more than 7%, the preceding elements together 3 to 14% of the total weight, 3 to 9% of aluminium, 17 to 21% manganese, 1 to 7% of zinc, with the balance being copper and incidental impurities.

2. An alloy according to claim 1 characterized in that the total amount of arsenic, antimony and phosphorus is less than 0.008%.

3. A copper base alloy containing manganese and aluminium, having the following composition: 1 to 6.5% of iron, 1 to 6.5% of nickel, the preceding elements together constituting 5 to 9% of the total weight, 3 to 9% of aluminium, 17 to 21% of manganese, 2 to 5% zinc, with the balance being copper and incidental impurities.

4. An alloy according to claim 3, having the following composition: 3 to 5% of iron, 1 to 3% of nickel, 4.5 to 6% of aluminium, 17 to 21% of manganese, 3 to 5% of zinc, with the balance being copper and incidental impurities.

5. An alloy according to claim 3, characterized in 10 that it has an aluminium content of 6.5 to 9%.

References Cited in the file of this patent UNITED STATES PATENTS 1,962,606 Masing et al June 12, 1934 

1. A COPPER BASE ALLOY CONTAINING MANGANESE AND ALUMINIUM, HAVING THE FOLLOWING COMPOSITION: 1 TO 9% OF IRON, UP TO 7% NICKEL, UP TO 7% COBALT, NICKEL AND COBALT TOGETHER NOT MORE THAN 7%, THE PRECEEDING ELEMENTS TOGETHER 3 TO 14% OF THE TOTAL WEIGHT, 3 TO 9% OF ALUMINIUM, 17 TO 21% MANAGANESE, 1 TO 7% OF ZINC, WITH THE BALANCE BEING COPPER AND INCIDENTAL IMPURITIES. 